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kilo- Prefix "thousand"

19th cent. Borrowed from French kilo- 'id.,' itself borrowed from Ancient Greek χίλιοι ‎(khílioi) 'id.' From Proto-Indo-European *ghes-lo- "thousand," "a great number." The same root as mil.

Indo-European: Indo-Iranian: Sanskrit sahásra- "thousand," Avestan hazaŋra- 'id.'